Evolutionary insights into NDM variants: Identification and functional analysis of novel NDM-58 in Pseudomonas aeruginosa.

The emergence of New Delhi Metallo-β-lactamase (NDM) variants in P. aeruginosa has significantly contributed to carbapenem resistance, posing a global threat to antimicrobial therapy. The catalytic activity of NDM, dependent on Zn (II), is enhanced by specific mutations. In this study, we report the identification and characterization of a novel NDM-58 variant (GenBank: OR081828.1) in P. aeruginosa BA24848, which exhibited resistance to multiple β-lactams, including cephalosporins, carbapenems, and BL/BLI combinations. WGS revealed that NDM-58 harbors a unique P185S substitution. This strain is associated with other ARGs (blaPAO, PME-1, fosA, blaOXA-396, blaOXA-494, blaOXA-50, sul1, dfrA1, qacE, aph(3')-VI, qnrVC1, and cat7), indicating a XDR phenotype. Comparative genomic analysis revealed the presence of MGEs (ISpre2, ISPa6, ISPa2, ISPsy29, IS26, Tn4661, ISPa37, and ISUnCu4) associated with NDM-58, which may facilitate the horizontal transfer of resistance determinants. Structural modeling and molecular dynamics simulations demonstrated that NDM-58 exhibits altered stability and compactness compared to NDM-1, likely influencing its enzymatic activity and resistance profile. Residual conservation analysis revealed that Pro185 is highly conserved, and its substitution to serine may impact protein stability and function. The molecular dynamics analysis indicated that NDM-58 has lower residual fluctuations and increased flexibility, which may enhance its adaptability under varying physiological conditions. Our findings provide novel insights into the evolutionary dynamics of NDM enzymes and the role of genetic environments in their dissemination. Understanding these mechanisms is crucial for developing effective surveillance and mitigation strategies against emerging carbapenem-resistant P. aeruginosa.